The symbol dBrn or dB(rn) is an abbreviation for

decibels The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a Power, root-power, and field quantities, power or root-power quantity on a logarithmic scale. Two signals whose ...

above

reference noise In telecommunication, reference noise is the magnitude of circuit noise chosen as a reference for measurement. Many different levels with a number of different weightings are in current use, and care must be taken to ensure that the proper param ...

. Weighted

noise power In telecommunication, the term noise power has the following meanings: # The measured total noise in a given bandwidth at the input or output of a device when the signal is not present; the integral of noise spectral density over the bandwidth # T ...

in dB is referred to 1.0

picowatt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James Watt ...

. Thus, 0 dBrn = -90

dBm DBM or dbm may refer to: Science and technology * dBm, a unit for power measurement * DBM (computing), family of key-value database engines including dbm, ndbm, gdbm, and Berkeley DB * Database Manager (DBM), a component of 1987's ''Extended Edi ...

. Use of 144

line Line most often refers to: * Line (geometry), object with zero thickness and curvature that stretches to infinity * Telephone line, a single-user circuit on a telephone communication system Line, lines, The Line, or LINE may also refer to: Arts ...

, 144-receiver, or C-message weighting, or

flat weighting In a noise-measuring set, flat weighting is a noise weighting based on an amplitude-frequency characteristic that is flat over a frequency range that must be stated. Notes * ''Note 1:'' Flat noise power is expressed in dBrn The symbol dBrn or dB ...

, can be indicated in

parentheses A bracket is either of two tall fore- or back-facing punctuation marks commonly used to isolate a segment of text or data from its surroundings. Typically deployed in symmetric pairs, an individual bracket may be identified as a 'left' or 'r ...

. With C-message weighting, a one-

milliwatt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James Watt ...

, 1000 Hz tone will read +90 dBrn, but the same power as

white noise In signal processing, white noise is a random signal having equal intensity at different frequencies, giving it a constant power spectral density. The term is used, with this or similar meanings, in many scientific and technical disciplines, ...

, randomly distributed over a 3 kHz

band Band or BAND may refer to: Places *Bánd, a village in Hungary *Band, Iran, a village in Urmia County, West Azerbaijan Province, Iran *Band, Mureș, a commune in Romania * Band-e Majid Khan, a village in Bukan County, West Azerbaijan Province, I ...

will read approximately +88.5 dBrn, because of the

frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...

weighting. With 144 weightings, a one milliwatt, 1000 Hz white noise tone will also read +90 dBrn, but the same 3 kHz power will only read +82 dBrn, because of the different

frequency weighting A weighting filter is used to emphasize or suppress some aspects of a phenomenon compared to others, for measurement or other purposes. Audio applications In each field of audio measurement, special units are used to indicate a weighted measure ...

. Note: In telecommunications, ''dBrn adjusted'' also called dBa denotes "decibels adjusted", i.e. weighted absolute noise power. This is totally unrelated to and not a synonym for

dB(A) A-weighting is the most commonly used of a family of curves defined in the International standard IEC 61672:2003 and various national standards relating to the measurement of sound pressure level. A-weighting is applied to instrument-measured s ...

References

{{lowercase Mechanics Units of measurement Logarithmic scales of measurement